Insulated conductor.



I J. I. MITCHELL. INSULATEDOOHDUGTOR. APPLICATION FILED 3331214, 1903.

Patented Dec. 1,1908,

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JOSEPH I. MITCHELL, OF SCHENECTADY, NEW YORK. ASSIGNOR .TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

INSULATED CONDUCTOR.

Specification of Letters Patent.

Patented Dec. 1, 1908.

Application filed September 14, 1993- Serial No. 173,07.

useful Improvements in Insulated Conductors, of which the following is aspecification.

The use of conductors in the form of rib-.

bone or strips as distinguished from Wires or rods has been found highlyadvantageous in various linesof electrical a paratus. For instance thesestrips or 'ri' bons are frequently bent edgewise to -formcurrentcarrying coils or windings for transformers, field magnets or thelike. Some difficulty has heretofore been experienced in insulating suchconductors. These difficulties have been due in art to the severemechanical strains to w ich the insulation is subject when the insulatedconductor is bent as in the formation of edgewise-wound coils. It hasalso been found that small spines or slivers of the conducting materialsometimes project from the conductor and these spines or sliversoccasionally penetrate the insulation and establish contact betweenlayers of the same coil 01' with other conductin terial in proximit tothe conductor. l have discovered that t ese difiiculties can be doneaway with by the employment of a strip or ribbon of strong paper orsimilar insulating material secured at one or both sides of the strip ofconducting material. In carrying out my invention I place the strips ofconducting material and insulation with their edges parallel and incasethem in a single layer of cotton, silk or the like, which is woven orbraided about the conducting and insulating strips. With thisconstruction the paper or similar insulating material is held firmly inplace by the woven or braided jacket and is not unduly distorted by thecoil-forming or similar operations. Moreover the stron paper or the likeis not penetratedby the me spines projecting from the conductor andhence the dii'liculty from this cause is avoided. The woven jacket alsoadds to the insulation.

For a better understanding of my invention reference may be had to theaccom-- panying drawings in which I have illustrated embodiments of myinvention.

Of the drawings E' ure 1 is a perspective view illustrating coil formedfrom an edge Wise-wound insulated conductor constructed 5 in accordancewith my invention; Fig. 2 is an enlarged view showing an insulatedconductor consisting of one layer of conducting material and one layerof insulating material; Eig'. 3 is a similar view showing a conductorprovided with a layer of insulating material at each side of the stripor ribbon of conducting material; and Fig. 4 illustrates a modifiedarrangement of the insulating layer.

Referring to Fig. 2 or the drawings, a ribcopper is shown as placed sideby side with a layer or strip 2 of insulating material such as paper,hard fiber, sheet mica, compositions containing one or more of thesematerials or the like. A textile jacket 3 of cotton, silk. or the likeis woven or braided about the conducting strip 1 and the strip ofinsulating material 2. In practice I prefer to assemble the conductingstrip and the insulating strip and to surround them with the woven orbraided jacket simultaneously though it is not essential that this bedone.

"When the insulated conductor is Wound into a coil in the manner shownin Fig. 1, it will be seen that each turn of the conducting strip is searated from adjacent turns by one layer of t e paper or similar material2 and two layers of the woven fabric 3.

layer 2 of paper or the like is placed at each side of the conductingstrip, and the three layers are then inclosed in a single jacket. Itwill be readily understood that in a coil constructed out of aninsulated conductor formed in the manner described each turn of theconducting material would be separated by two layers of the paper or thelike as well as by two layers of the woven fabric.

It will of coursebe obvious that more than one thickness of the paper orthe like and more than one thickness of the conducting material may beemployed to form the layers 2 and 1 respectively. As before stated, theexact compositions of the insulating material out of which the layerorlayers 2 are formed is immaterial. I have obtained very good resultsin some instances from the use of an insulation composed of a strip ofpaper upon which scales or pieces of mica are secured by glue or thelike. A coil formed out of sucli'an insulated conductorzpossesse' the Inthe construction shown in Fig. 3 a

bon or strip 1 of conducting material such as further advantage that itis practically fireproof since the mica which forms the major ortion ofthe insulation is practically unaftected by fire.

Nhile ordinarily it is sufl'icient to employ strips of paper or the likeof a width equal to that of the conducting strips, as shown in Figs. 1,2 and 3, it may in some instances be desirable to employ strips ofinsulating matel; rial Wider than the strip of conducting material. insuch cases the insulating material may, if desired, be turned up at theedges so that the paper or a similar material forms a trough in whichthe conducting strip is placed, as shown in Fig. l \Vhcn the strips ofpaper or the like are not greater in width than the strips of conductingmaterial, the edges of the conducting strips are of course protectedonly by the woven fabric. This, however, is sufiicient for manypurposes.

\Vhat I claim as new, and desire to secure by Letters Patent of theUnited States, is, A conductor adapted for use in making edgewise-woundCOIlS consisting of a flat strip or ribbon of conducting material, aflat strip or ribbon of insulating material lying against one side ofthe strip of conducting material, and a textile jacket fitting saidassembled strips so as to hold them'against relative displacement InWitness whereof I have liereuntojset my hand this 12th day of September,1903.

JOSEPH .l. MITCHELL. Witnesses:

BENJAum B. HULL. HELEN ()RFmw.

